Two-piece barrel nut

ABSTRACT

A two-piece barrel nut includes an internal nut with an externally threaded portion on one end and a plurality of engageable members on the opposite end, and an external nut with an internally threaded portion on one end that receives the externally threaded portion of the internal nut and one or more receptacles on the other end that each may receive a fastener that engages at least one of the plurality of engageable members on the internal nut to lock the external nut to the internal nut. A method for using the barrel nut to attach a barrel to a firearm is also disclosed.

BACKGROUND

1. Technical Field

This disclosure generally relates to firearms, and more specificallyrelates to a barrel nut for a rifle.

2. Background Art

The AR-15 rifle is one of the most popular rifle platforms in the world.An AR-15 rifle typically includes a lower receiver, an upper receiver,and a barrel connected to the upper receiver. A stock and front grip arealso typically included. Various other items may be optionally includedon an AR-15 rifle, such as front and/or rear sights, a flash suppressor,a bayonet mount, a rail system, various optics including scopes andred-dot sights, tactical lights, sling mounts and slings, etc. Becausethe design of the lower receiver and upper receiver is uniform betweenmost manufacturers, many different manufacturers make AR-15 lowerreceivers and upper receivers and parts that are interchangeable. Thus,a person can typically take an AR-15 lower receiver made by a firstmanufacturer and mate it to an AR-15 upper receiver made by a secondmanufacturer that is connected to a barrel made by a third manufacturer.This interchangeability of parts, along with the vast number ofdifferent accessories that can be added, makes the AR-15 an extremelypopular rifle among rifle enthusiasts.

The barrel of an AR-15 is connected to the upper receiver using a barrelnut. Referring to FIG. 1, an upper receiver 110 is shown with anexternally threaded boss 120. A barrel 130 includes a back portion 140dimensioned to slide within the interior of the threaded boss 120, witha flange 150 that abuts the face of the threaded boss 120 when thebarrel is installed into the upper receiver 110. Once the back portion140 of barrel 130 is slid into the threaded boss 120 until the flange150 contacts the front face of the threaded boss 120, a barrel nut isthen slid over the free end of the barrel and down the barrel, and isthen screwed onto the threads of the threaded boss 120 to secure thebarrel 130 to the upper receiver 110.

Various barrel nuts for the AR-15 rifle have been developed over theyears. Many of these barrel nuts require separate mounting systems for afront grip, many of which contact the barrel, which reduces accuracy.Some barrel nuts include threaded holes for mounting a front grip, butthese also contact the barrel, which reduces accuracy.

BRIEF SUMMARY

A two-piece barrel nut includes an internal nut with an externallythreaded portion on one end and a plurality of engageable members on theopposite end, and an external nut with an internally threaded portion onone end that receives the externally threaded portion of the internalnut and one or more receptacles on the other end that each may receive afastener that engages at least one of the plurality of engageablemembers on the internal nut to lock the external nut to the internalnut. A method for using the barrel nut to attach a barrel to a firearmis also disclosed.

In one specific configuration, the internal nut includes an externallythreaded portion on one end and a scalloped edge on the opposite endthat provides a plurality of substantially concave portions asengageable members. The external nut has one or more screw holes on thefront face of the external nut. When the internal nut is screwed intothe external nut in a proper position, the scalloped edge is inproximity to the screw holes on the front face such that when aretaining screw is installed into the external nut, a head portion ofthe retaining screw engages one of the substantially concave portions onthe scalloped edge of the internal nut, thereby locking the internal nutto the external nut. Aligning a gas tube slot on the external barrel nutto the appropriate gas tube location is easy because the scalloped edgeof the internal nut allows small rotational increments in adjusting theposition of the internal barrel nut with respect to the external barrelnut.

The foregoing and other features and advantages will be apparent fromthe following more particular description, as illustrated in theaccompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

The disclosure will be described in conjunction with the appendeddrawings, where like designations denote like elements, and:

FIG. 1 is shows an upper receiver and a barrel for an AR platform rifle;

FIG. 2 is a perspective view of a prior art barrel nut;

FIG. 3 is a front view of one suitable configuration of an internalbarrel nut;

FIG. 4 is a side view of the internal barrel nut in FIG. 3 taken alongthe line 4-4;

FIG. 5 is a front view of one suitable configuration of an externalbarrel nut;

FIG. 6 is a side view of the external barrel nut in FIG. 5 taken alongthe line 6-6;

FIG. 7 is a front view showing the two-piece barrel nut with theinternal barrel nut installed in the external barrel nut and locked intoposition with respect to the external barrel nut by installing retainingscrews into a first set of opposing holes;

FIG. 8 is a front view showing the two-piece barrel nut with theinternal barrel nut installed in the external barrel nut and locked intoposition with respect to the external barrel nut by installing retainingscrews into a second set of opposing holes;

FIG. 9 is flow diagram of a method for installing a barrel into an upperreceiver using the two-piece barrel nut disclosed herein;

FIG. 10 is a front view of the two-piece barrel nut illustrating therotation of the internal nut while holding the external nut in a desiredposition, as described in step 925 of FIG. 9;

FIG. 11 is a front view of the two-piece barrel nut showing a slightrotation of the internal nut to align the concave portions of thescalloped edge of the internal nut with one of the pairs of opposingholes, as described in step 940 of FIG. 9; and

FIG. 12 is a front view of the two-piece barrel nut in FIG. 11 after theinternal nut is rotated to align the concave portions of the scallopededge of the internal nut with one of the pairs of opposing holes and tworetaining screws are installed to lock the external nut to the internalnut.

DETAILED DESCRIPTION

The AR-15 rifle is typically chambered for the 5.56 mm×45 mm NATO round.A variation of the AR-15 known as the AR-10 uses the same basic designfor the 7.62 mm×51 mm round. Many of the parts in an AR-10 are verysimilar to the corresponding parts in an AR-15, but are sometimes largerand stronger to accommodate the larger, more powerful round. Forexample, the barrel nut on an AR-10 is typically larger in diameter thanthe barrel nut on an AR-15 to accommodate the thicker barrel. Butbesides the diameter, the design is very similar. The AR-10 and AR-15are referred to herein as the “AR platform” because different sizes ofthe barrel nut disclosed herein can be used on AR-10 and AR-15 rifles.

Many different barrel nuts have been developed for the AR platform overthe years. One prior art barrel nut is shown at 200 in FIG. 2. Barrelnut 200 includes an internally threaded portion 220 designed to screwonto the threads of a threaded boss on an AR platform upper receiver,such as 120 in FIG. 1. Barrel nut 200 further includes a reduceddiameter portion 230 that engages the flange 150 shown in FIG. 1 tosecure the barrel to the upper receiver. One of the features of the ARplatform is a gas tube that runs from the top of the upper receiveralong the top of the barrel. To accommodate the gas tube, the barrel nut200 has a scalloped face with multiple recesses, three of which areidentified in FIG. 2 at 210. The barrel nut 200 can be tightened tosecure a barrel on a threaded boss of an upper receiver. The barrel nut200 shown in FIG. 2 includes twenty recesses 210. Thus, once a barrelnut has been tightened to the lower range of specified torque, thebarrel nut can typically be tightened a little more, if needed, to alignone of the recesses 210 to the gas tube location on the upper receiver.With twenty recesses along the perimeter of the barrel nut, the rotationbetween recesses is 18°, which means the most the nut must be tightenedor loosened to align a recess with the gas tube location on the upperreceiver is less than 18°.

Some front grips use a clamshell-type configuration to attach a frontgrip to a prior art barrel nut such as 200 shown in FIG. 2. Many ofthese clamshell-type configurations attach the forward part of the frontgrip to the barrel. Newer barrel nuts have been developed that includethreaded screw holes for attaching a front grip directly to the barrelnut that allow the front grip to float with respect to the barrel,meaning the front grip is not attached to the barrel. A barrel nut usedby Black Rain Ordinance in Neosho, Mo. on their AR platform rifles is atwo-piece barrel nut that includes an external nut and an internal nutthat screws into the external nut. Threaded holes are provided in theexternal nut so that once the appropriate position of the internal nutwith respect to the external nut is determined, set screws are installedinto the external nut and are tightened to lock the external nut to theinternal nut. The problem with using set screws is the pressure of theset screw against the internal nut often causes the internal nut todeform and contact the barrel. It has been recognized over the yearsthat having anything touch the barrel of an AR platform rifle anywherealong the barrel's length reduces the accuracy of the rifle. Thus, whilethe two-piece barrel nut used by Black Rain allows the front grip tofloat with respect to the barrel by providing threaded holes formounting the front grip on the barrel nut, the advantage of the floatingfront grip is somewhat nullified by the internal nut of the two-piecebarrel nut contacting the rifle barrel due to the force of the setscrews that lock the internal nut to the external nut. This results indecreased accuracy.

Other two-piece barrel nuts have been developed that allow for moreeasily aligning a gas tube slot on the barrel nut with a gas tubelocation on the upper receiver. Most of these two-piece barrel nuts donot include threaded holes for attaching a front grip. As a result, animproved barrel nut is needed.

A two-piece barrel nut includes an internal nut with an externallythreaded portion on one end and a plurality of engageable members on theopposite end, and an external nut with an internally threaded portion onone end that receives the externally threaded portion of the internalnut and one or more receptacles on the other end that each may receive afastener that engages at least one of the plurality of engageablemembers on the internal nut to lock the external nut to the internalnut. A method for using the barrel nut to attach a barrel to a firearmis also disclosed. The barrel nut includes threaded holes for mounting afront grip to the barrel nut. Using the barrel nut disclosed hereinresults in a barrel that truly floats and is not contacted along itslength by either the barrel nut or the front grip.

FIG. 3 shows a front view of one specific implementation for theinternal nut 300 of the barrel nut disclosed and claimed herein. Notethe term “front” as used herein refers to the side that is viewable whenlooking in the same direction as one looking down the bore of thebarrel, while the “back” is the opposite side. FIG. 4 shows a side viewof the barrel nut in FIG. 3 taken along the line 4-4. The internal nut300 preferably has a substantially hollow cylindrical shape. Theinternal nut 300 includes a scalloped edge 310 on the front end and anexternally threaded portion 410 on the back end. The scalloped edge 310defines multiple substantially concave portions, three of which areshown at 320 in FIGS. 3 and 4. The substantially concave portions 320are engageable members that can be engaged by one or more fastenersfastened to the external nut to lock the internal nut 300 to theexternal nut. In the specific configuration shown in the figures, theinternal nut 300 includes twenty-four substantially concave portions.The externally threaded portion 410 preferably includes threads of thesame size and pitch as the threads on the threaded boss on the upperreceiver.

One specific implementation of the external nut of the two-piece barrelnut as disclosed and claimed herein is shown at 500 in FIGS. 5 and 6.The external nut 500 preferably has a substantially hollow cylindricalshape. The external nut 500 includes an internally threaded portion 610at its back and one or more receptacles on the front end for receiving afastener that engages one or more of the engageable members on theinternal nut to lock the external nut to the internal nut. In thespecific configuration shown in FIGS. 5 and 6, the receptacles arethreaded screw holes 510. As shown more clearly in FIG. 6, each threadedscrew hole 510 includes a countersink portion 520 for receiving a flathead of a screw installed in the threaded screw hole 510. Because thescrew holes 510 are placed close to the inner wall 580 of the externalnut, when a screw is installed into a screw hole 510, part of the headof the screw extends beyond the inner wall 580 of the external nut 500to engage one of the engageable members on the internal nut, therebylocking the internal nut to the external nut, as shown more clearly inFIGS. 7, 8 and 12.

In the specific configuration for external nut 500 shown in thedrawings, four screw holes 510 are provided on the front face of theexternal nut 500, as shown in FIG. 5. The front face 620 of the externalnut 500 is most of what is visible in FIG. 5 and is the right edge shownin FIG. 6. The front face 620 of the external nut 500 preferably lies ina plane that is normal to a longitudinal axis of the external nut 500.The four screw holes 510 are in the form of first and second pairs ofopposing threaded holes. Thus, in FIG. 5, a first pair of opposingthreaded holes is shown by a line 560 through the corresponding holes510. A second pair of opposing threaded holes is shown by a line 570through the corresponding holes 510. Note the lines 560 and 570 arepreferably at an angle of 82.5° with respect to each other. Because thescalloped edge 310 of the internal nut 300 preferably has twenty-foursubstantially concave portions 320, this means there is a rotationalangle of 15° between the substantially concave portions 320. Byoffsetting the first and second pairs of opposing threaded holes by82.5°, this means the internal nut can be adjusted with respect to theexternal nut in 7.5° increments.

The external nut 500 includes two gas tube slots 540 along its length.Providing two gas tube slots instead of one provides greateradjustability in using the barrel nut disclosed herein. The external nut500 also includes opposing recesses 550. The recesses 550 are providedto allow a tool with three or four round posts appropriately spaced tobe used to tighten the barrel nut onto an upper receiver by placing twoor more of the posts in the gas tube slots 540 and/or the opposingrecesses 550. The external nut 500 includes threaded holes 530 formounting a front grip to the external nut 500 after the barrel nut isproperly installed. In the configuration shown in FIGS. 5 and 6, thereare eight total holes 530, four on each side of each gas tube slot 540.Thus, regardless of which gas tube slot is selected for alignment withthe gas tube location on the upper receiver, four threaded holes 530 arecorrectly aligned for mounting a front grip.

FIG. 7 shows the two-piece barrel nut 700 assembled with the externalnut 500 locked to the internal nut 300 by the heads of two screws 710.The heads of the screws 710 extend beyond the inner wall of the externalnut 500 and each engages one of the engageable members to lock theexternal nut 500 to the internal nut 300. Because the two pairs ofopposing holes are offset by 82.5°, when one set of holes is alignedwith the engageable members, the other set of holes is not aligned withany of the engageable members. Thus, as shown in FIG. 7, when the firstset of holes that have screws 710 align with the engageable members asshown, the two empty screw holes 510 are not aligned with any engageablemembers. In similar fashion, as shown in FIG. 8, when the internal nutis rotated 7.5°, the second pair of opposing holes aligns with theengageable members as shown by the screws 710, while the first pair ofopposing holes is not aligned with any of the engageable members. Byproviding an angular offset between opposing holes, the internal nut hasan adjustability with respect to the external nut in 7.5° increments.

FIG. 9 shows one suitable method 900 for attaching a barrel to an upperreceiver of an AR platform rifle using a two-piece barrel nut as shownin FIGS. 3-6. The back of the barrel is slid into the threaded boss ofthe upper receiver (step 910). The barrel nut is then assembled byscrewing the internal nut into the external nut until the scalloped edgeof the internal nut extends beyond the front face of the external nut(step 915). The barrel nut is then slid over the front of the barrel tothe threaded boss of the upper receiver (step 920). The threads of theexternal nut are then screwed onto the threaded boss until the back faceof the external nut is a desired distance from the upper receiver, withone of the two gas tube slots positioned at a selected angular offsetfrom gas tube location in the upper receiver (step 925). The desireddistance can be any suitable distance, and is preferably 1.5-3.0 mm. Oneof the gas tube slots is preferably aligned at a selected angular offsetwith respect to the gas tube location on the upper receiver that isestimated such that when the barrel nut is tightened to an appropriatetorque specification, the gas tube slot will align with the gas tubelocation.

While holding the external nut in the desired position with one hand,the internal nut is screwed into the external nut with the other handuntil the back of the internal nut contacts the barrel flange (step930). This can be done, for example, by using a small hex wrench orscrewdriver to push on one of the substantially concave portions of thescalloped edge to rotate the internal nut while holding the external nutin place. The barrel nut is then unscrewed from the threaded boss of theupper receiver and is slid off the barrel (step 935). The relativeposition of the internal nut to the external nut is then examinedvisually. If neither of the pairs of opposing holes align with thescallops in the scalloped edge of the internal nut, this means theinternal nut needs to be rotated slightly. Thus, if needed, the internalnut is rotated slightly within the external nut to align the scallops onthe internal nut with one of the two sets of screw holes in the frontface of the external nut (step 940). As discussed above, the offsetscrew holes provide an adjustment increment of 7.5°, so the amount ofadjustment required will be less than 7.5°. Once the internal nut isaligned so its scallops align with the screw holes on the external nut,retaining screws are installed on the front face of the external nut tolock the internal nut to the external nut (step 945), as shown in FIG. 7or 8. The barrel nut is then slid over the front of the barrel to thethreaded boss of the upper receiver (step 950). The threads of theexternal nut are screwed onto the threaded boss of the upper receiveruntil hand tight (step 955). A gas tube slot on the barrel nut will thenbe aligned approximately where it was when the barrel nut was lastremoved from the barrel. The external nut is then tightened using asuitable wrench designed to engage two or more of the gas tube slots 540and the opposing recesses 550. The external nut is tightened to bewithin a specified range of torque until the gas tube slot on theexternal nut is aligned with the gas tube location (step 960). At thispoint, a front grip may be attached to the threaded holes 530 on theexternal nut 500.

The process of screwing the internal nut into the external nut in step930 and the locking of the external nut to the internal nut in steps 940and 945 are shown graphically in FIGS. 10-12. We assume the line 1010 inFIG. 10 represents a desired gas tube location on an upper receiver,which is typically directly on top of the barrel. In step 925 in FIG. 9,once the external nut is threaded onto the threads of the threaded bosson the upper receiver until it is at the desired distance from the upperreceiver, the gas tube slots on the external nut are then inspected withrespect to a desired gas tube location on the upper receiver. Theexternal barrel nut may then be rotated a small amount until one of thegas tubes is at a desired angle 1020 with respect to the gas tubelocation 1010, as shown in FIG. 10. This angle 1020 is preferably lessthan 90 degrees, is more preferably less than 60 degrees, and is mostpreferably less than 45 degrees. In FIG. 10, the gas tube slot 540 isshown approximately 40 degrees from the gas tube location 1010. Theappropriate angle will depend on the thread pitch and torque used totighten the barrel nut, and an angle of substantially less than 45degrees may be suitable. A skilled worker will quickly learn theappropriate angle to use to achieve the desired level of torque on thebarrel nut when the gas tube slot 540 aligns with the gas tube location1010.

In step 930 in FIG. 9, a person holds the external nut in the positionshown in FIG. 10 with one hand while screwing the internal nut into theexternal nut until the back face of the internal nut contacts the barrelflange. This rotation of the internal nut is shown by the arrow in FIG.10, and can take more than a full revolution before the back of theinternal barrel nut contacts the barrel flange. The barrel nut is thenremoved in step 935. We assume after steps 930 and 935 the internal nutand external nut have the rotational relationship shown in FIG. 11. Notethe scallops on the internal nut 300 in FIG. 11 are not aligned with anyof the holes 510. As a result, the internal nut 300 needs to be rotatedslightly until the scallops are aligned with one of the sets of holes.The arrow in FIG. 11 denotes the internal nut is rotated with respect tothe external nut a slight amount until the scallops align with one ofthe sets of screw holes, as shown in FIG. 12. This corresponds to step940 in FIG. 9. Once aligned, the retaining screws are installed, asshown at 710 in FIG. 12, which corresponds to step 945 in FIG. 9. Notethe internal nut could have been rotated in the opposite direction thanthe direction shown in FIG. 11, which would result in the screws beinginstalled in the other pair of opposing holes. The two sets of opposingholes provide 7.5° increments of adjustability between the internal nutand the external nut.

With the internal nut 300 and external nut 500 locked together using theretaining screws as shown in FIG. 12, the barrel nut is once againplaced over the barrel and screwed onto the threaded boss of the upperreceiver until hand tight, as shown in step 955 in FIG. 9. At that pointthe barrel nut will have a rotational orientation similar to that shownin FIG. 10. In step 960, a person uses an appropriate tool to rotate theexternal nut 500 until the gas tube slot 540 aligns with the gas tubelocation 1010 in FIG. 10. In other words, for the specific example inFIG. 10, the barrel nut is rotated about 40 degrees for the gas tubeslot 540 to align with the gas tube location 1010. The rotation of thebarrel nut to the point of the gas tube slot aligning with the gas tubelocation tightens the barrel nut and preferably achieves the desiredlevel of torque for the barrel nut. Once the barrel nut is installed, afront grip can be attached to the barrel nut, allowing both the barrelnut and front grip to float with respect to the length of the barrel.

While method 900 includes steps that are specific to the design of theinternal nut and external nut shown in FIGS. 3-6, one skilled in the artwill recognize that similar steps could also be performed for differentconfigurations. For example, different receptacles and fasteners anddifferent engageable portions may require different steps. Method 900 isprovided as an example, and should not be construed as limiting.

The desired level of torque can vary according to the materials used inthe upper receiver. Most AR platform rifles use 35-70 ft-lbs (47-95newton meters) of torque on the barrel nut when the upper receiver isforged. However, when the upper receiver is made of a more durablematerial such as 7075 aluminum, the barrel nut may be tightened to atorque of up to 150 ft-lbs (203 newton meters).

In the version of the two-piece barrel nut for an AR-15 rifle, the upperreceiver has threads on the threaded boss of 18 threads per inch (7.09threads per cm), which means the internally threaded portion 610 of theexternal nut 500 has a corresponding 18 threads per inch (7.09 threadsper cm) and the externally threaded portion 410 of the internal nut 300also has 18 threads per inch (7.09 threads per cm). This means screwingthe barrel nut one full rotation will move the barrel nut linearly 1/18inch, or 0.05556 inch (1.41 mm). Because the barrel nut disclosed in thefigures herein provides 7.5° increments of adjustability between theinternal nut and the external nut, this means one increment ofadjustment moves the barrel nut 0.005556/48 or 0.00116 inch (0.029 mm).This fine grain adjustability provides a barrel nut that is easy toinstall.

In the version of the barrel nut for an AR-10 rifle, the upper receiverhas threads on the threaded boss of 16 threads per inch (6.3 threads percm), which means the internally threaded portion 610 of the external nut500 has a corresponding 16 threads per inch (6.3 threads per cm) and theexternally threaded portion 410 of the internal nut 300 also has 16threads per inch (6.3 threads per cm). This means screwing the barrelnut one full rotation will move the barrel nut 1/16 inch, or 0.0625 inch(1.59 mm). Because the barrel nut disclosed in the figures hereinprovides 7.5° increments of adjustability between the internal nut andthe external nut, this means one increment of adjustment moves thebarrel nut 0.00625/48 or 0.0013 inch (0.033 mm). Once again, this finegrain adjustability provides a barrel nut that is easy to install.

The two-piece barrel nut disclosed herein is a significant improvementto the two-piece barrel nut used by Black Rain Ordinance discussedabove. Because the screws that lock the internal nut to the external nutare on the front face of the barrel nut, there is no pressure from setscrews that causes the internal barrel nut to deform and contact thebarrel. As a result, the barrel nut disclosed and claimed herein doesnot contact the barrel at any location except the barrel flange, andprovides mounting holes for a front grip. With an AR platform rifle witha machined upper receive made of 7075 aluminum, the combination ofincreased torque on the barrel nut and the fact that neither the barrelnut nor the front grip contact the barrel anywhere except the barrelflange results in an AR platform rifle with increased accuracy.

A two-piece barrel nut includes an internal nut with an externallythreaded portion on one end and a plurality of engageable members on theopposite end, and an external nut with an internally threaded portion onone end that receives the externally threaded portion of the internalnut and one or more receptacles on the other end that each may receive afastener that engages at least one of the plurality of engageablemembers on the internal nut to lock the external nut to the internalnut. A method for using the barrel nut to attach a barrel to a firearmis also disclosed.

The disclosure and claims herein disclose a barrel nut comprising aninternal nut in a substantially hollow cylindrical shape comprising: anexternally threaded portion on a first end; and a plurality ofengageable members on a second end opposite the first end; an externalnut in a substantially hollow cylindrical shape comprising: aninternally threaded portion on a first end that receives the externallythreaded portion of the internal nut; and at least one receptacle on asecond end opposite the first end for receiving a fastener that engagesat least one of the plurality of engageable members on the internal nutto lock the external nut to the internal nut.

The disclosure and claims herein disclose a barrel nut comprising: aninternal nut in a substantially hollow cylindrical shape comprising: anexternally threaded portion on a first end; and a scalloped edge on asecond end opposite the first end that provides a plurality ofsubstantially concave members around the perimeter of the second end; anexternal nut in a substantially hollow cylindrical shape comprising: aninternally threaded portion on a first end that receives the externallythreaded portion of the internal nut; and a plurality of threaded holeson a second end opposite the first end for receiving a screw having ahead portion that engages at least one of the plurality of substantiallyconcave members on the internal nut to lock the external nut to theinternal nut.

The disclosure and claims herein disclose a method for attaching abarrel to a firearm, wherein the barrel includes a back portion and aflange, the method comprising: sliding the back portion of the barrelinto a threaded boss on the firearm; screwing an internal nut of abarrel nut into an external nut of the barrel nut, wherein the internalnut is in a substantially hollow cylindrical shape comprising: anexternally threaded portion on a first end; and a plurality ofengageable members on a second end opposite the first end; wherein theexternal nut is in a substantially hollow cylindrical shape comprising:an internally threaded portion on a first end that receives theexternally threaded portion of the internal nut; and at least onereceptacle on a front face of a second end opposite the first end forreceiving a fastener that engages at least one of the plurality ofengageable members on the internal nut to lock the external nut to theinternal nut; wherein the internal nut is screwed into the external nutuntil the second end of the internal nut extends beyond the front faceof the external barrel nut; sliding the barrel nut over a front of thebarrel to the threaded boss; screwing the internally threaded portion ofthe external nut onto the threaded boss until a back face of theexternal nut is a desired distance from a portion of the firearm and agas tube slot on the external nut is positioned to a selected angularoffset from a gas tube location on the firearm; while holding theexternal nut in position, screwing the internal nut into the externalnut until the back of the internal nut contacts the flange of thebarrel; unscrewing the barrel nut from the threaded boss of the upperreceiver; sliding the barrel nut off the barrel; if needed, rotating theinternal nut slightly within the external nut to align the at least onereceptacle on the external nut with at least one of the plurality ofengageable members on the internal nut; installing at least one fastenerinto the at least one receptacle to lock the internal nut to theexternal nut; sliding the barrel nut over the front of the barrel to thethreaded boss on the firearm; screwing the internally threaded portionof the external nut onto the threaded boss until hand tight; andtightening the external nut on the threaded boss to within a specifiedtorque range with the gas tube slot aligned with the gas tube location.

One skilled in the art will appreciate that many variations are possiblewithin the scope of the claims. Thus, while the disclosure isparticularly shown and described above, it will be understood by thoseskilled in the art that these and other changes in form and details maybe made therein without departing from the spirit and scope of theclaims. For example, while screw holes are disclosed as one suitableimplementation for a receptacle and screws are disclosed as one suitablefastener that can be used to lock the internal nut to the external nut,the disclosure and claims herein extend to any suitable receptacle(s)and fastener(s) that could be used to lock the internal nut to theexternal nut. Furthermore, while a scalloped edge that provides aplurality of substantially concave members around the perimeter of theinternal nut is shown in the figures as one example of a plurality ofengageable members on the internal nut, the disclosure and claims hereinexpressly extend to any suitable configuration that provides a pluralityof engageable members on the internal nut, whether currently known ordeveloped in the future. For example, instead of a scalloped edge thatprovides a plurality of substantially concave engageable portions, theinternal nut could provide an edge with notches similar to the top of acastle nut, where a screw head fastener could engage one of the notchesto lock the internal nut to the external nut. In addition, while twoscrews in opposing holes are shown as fasteners to lock the internal nutto the external nut, only one screw could be used, or more than twoscrews could be used. Furthermore, while the configuration disclosedhere shows a fastener engaging a single engageable member, otherconfigurations within the scope of the disclosure and claims herein canhave one or more fasteners that each engages two or more engageablemembers. In addition, while twenty four engageable members are shown inthe figures, other numbers and type of engageable members could be used.These and other variations are within the scope of the disclosure andclaims herein.

The invention claimed is:
 1. A barrel nut comprising: an internal nut ina substantially hollow cylindrical shape comprising: an externallythreaded portion on a first end; and a scalloped edge on a second endopposite the first end that provides a plurality of substantiallyconcave members around the perimeter of the second end; an external nutin a substantially hollow cylindrical shape comprising: an internallythreaded portion on a first end that receives the externally threadedportion of the internal nut; and a plurality of threaded holes on asecond end opposite the first end for receiving a screw having a headportion that engages at least one of the plurality of substantiallyconcave members on the internal nut to lock the external nut to theinternal nut.
 2. The barrel nut of claim 1 wherein the plurality ofthreaded holes comprises first and second pairs of opposing threadedholes, wherein the first pair of opposing threaded holes is offset at anangle from the second pair of opposing threaded holes such that when theinternal nut is in a first position with respect to the external nut thefirst pair of opposing threaded holes are aligned with at least one ofthe plurality of substantially concave members and the second pair ofopposing holes are not aligned with any of the plurality ofsubstantially concave members, and when the internal nut is in a secondposition with respect to the external nut the second pair of opposingthreaded holes are aligned with at least one of the plurality ofsubstantially concave members and the first pair of opposing holes arenot aligned with any of the plurality of substantially concave members,wherein the first and second pairs of threaded holes each includes acountersink portion for receiving the head portion of the screw, whereina portion of the head portion of the screw engages the at least one ofthe plurality of substantially concave members on the internal nut whenthe head portion of the screw is seated in the countersink portion. 3.The barrel nut of claim 1 wherein the scalloped edge comprises twentyfour of the plurality of substantially concave members.
 4. The barrelnut of claim 1 wherein the external nut further comprises at least onegas tube slot along a length of the external nut.
 5. The barrel nut ofclaim 1 wherein the external nut further comprises a second plurality ofthreaded holes for mounting a grip.
 6. The barrel nut of claim 1 whereineach of the plurality of threaded holes is on a front face of the secondend of the external nut.
 7. A barrel nut comprising: an internal nut ina substantially hollow cylindrical shape comprising: an externallythreaded portion on a first end; and a plurality of engageable memberson a second end opposite the first end; an external nut in asubstantially hollow cylindrical shape comprising: an internallythreaded portion on a first end that receives the externally threadedportion of the internal nut; and at least one receptacle on a second endopposite the first end for receiving a fastener that engages at leastone of the plurality of engageable members on the internal nut to lockthe external nut to the internal nut.
 8. The barrel nut of claim 7wherein each receptacle comprises a threaded hole and wherein thefastener comprises a screw that screws into the threaded hole, whereinthe screw includes a head portion that engages at least one of theplurality of engageable members on the internal nut.
 9. The barrel nutof claim 8 wherein the at least one receptacle comprises first andsecond pairs of opposing threaded holes, wherein the first pair ofopposing threaded holes is offset at an angle from the second pair ofopposing threaded holes such that when the internal nut is in a firstposition with respect to the external nut the first pair of opposingthreaded holes are aligned with at least one of the plurality ofengageable members and the second pair of opposing holes are not alignedwith any of the plurality of engageable members, and when the internalnut is in a second position with respect to the external nut the secondpair of opposing threaded holes are aligned with at least one of theplurality of engageable members and the first pair of opposing holes arenot aligned with any of the plurality of engageable members.
 10. Thebarrel nut of claim 9 wherein the first and second pairs of threadedholes each includes a countersink portion for receiving the head portionof the screw, wherein a portion of the head portion of the screw engagesthe at least one of the plurality of engageable members on the internalnut when the head portion of the screw is seated in the countersinkportion.
 11. The barrel nut of claim 10 wherein the plurality ofengageable members comprise a scalloped edge that provides a pluralityof substantially concave members around the perimeter of the second endof the internal nut, wherein at least one of the plurality ofsubstantially concave members receives a portion of the head portion ofthe screw to lock the external nut to the internal nut.
 12. The barrelnut of claim 11 wherein the scalloped edge comprises twenty four of theplurality of substantially concave members.
 13. The barrel nut of claim7 wherein the external nut further comprises at least one gas tube slotalong a length of the external nut.
 14. The barrel nut of claim 7wherein the external nut further comprises a plurality of threaded holesfor mounting a grip.
 15. The barrel nut of claim 7 wherein theinternally threaded portion of the external nut is dimensioned toreceive a threaded boss on a firearm, and wherein the externallythreaded portion of the internal nut includes threads of a same size andpitch as the threaded boss.
 16. The barrel nut of claim 7 wherein the atleast one receptacle is on a front face of the second end of theexternal nut.
 17. The barrel nut of claim 7 wherein an internal diameterof the internal nut is dimensioned for a barrel of a firearm to passthrough while a back face of the first end of the internal nut engages aflange of the barrel.
 18. The barrel nut of claim 7 wherein when thefastener is installed to engage at least one of the plurality ofengageable members on the internally threaded portion to lock theexternal nut to the internal nut, and the barrel nut is installed tofasten a barrel of a firearm on a receiver of a firearm, the internalnut contacts the barrel of the firearm only on a flange of the barreland nowhere else on the barrel.